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Swelling soft magnetic alloy characteristics and classification

Swelling soft magnetic alloy A kind of precision soft magnetic alloy with abnormal thermal expansion characteristics, also known as thermal expansion soft magnetic alloy, is widely used in the electronics industry, precision measuring instruments, precision instruments and cryogenic engineering and other fields. General metals and soft magnetic alloys expand when heated and the expansion increases linearly with increasing temperature. However, the thermal expansion curve of some soft magnetic alloys shows a point of inflection at a certain temperature (intersection of two slopes with different slopes, as shown in the figure As shown in Tk), the thermal expansion coefficient below the bending point is much lower than the normal thermal expansion coefficient above the bending point, and this phenomenon is called abnormal thermal expansion characteristics.
The expanded soft magnetic alloy is divided into a low-expansion soft magnetic alloy and a fixed-expansion soft magnetic alloy, and the latter is also called a sealed soft magnetic alloy. The average expansion coefficient of the low-expansion soft magnetic alloy below the bending point is lower than 3×10-6°C-1; the average expansion coefficient of the fixed expansion soft magnetic alloy below the bending point is approximately (4～10)×10-6°C. 1. The soft magnetic alloys for expansion mainly include Fe-Ni, Fe-Ni-Co, and Fe-Ni-Cr soft magnetic alloys. High-chromium steels and Co-Fe-Cr soft magnetic alloys are also used as expanded soft magnetic alloys. However, the amount is not great. In addition to having a specific thermal expansion coefficient, the expanded soft magnetic alloy also requires good sealing properties, weldability, corrosion resistance, workability, and free-machining properties depending on the application, and does not allow it to occur within the use temperature range. Swelling characteristics change phase change. Swelling soft magnetic alloys must accurately control the chemical composition of soft magnetic alloys during the manufacturing process. The products are generally bars, plates, strips, wires and pipes.
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1. Iron nickel cobalt glass soft magnetic alloy FeNi29Co17
Grade: 4J29 (Kovar) Also called Kovar soft magnetic alloy (Fe54%, Ni29% and Co17%), its expansion coefficient is 4.7×10-6/°C.
Executive Standard: YB/T 5231-93
Uses: Used for matching and sealing of hard glass. Suitable for carbon brush factory launch tube, oscillation tube, igniter tube, transistor and tube plug, relay shell and other electrical vacuum devices. It has a certain coefficient of linear expansion in the temperature range of -60°C~+40°C, and it can be matched with hard glass for tight sealing.
Delivery status: strip, wire rod, round bar, forging [1]

2. Porcelain seal soft magnetic alloy Grade: Vacodil42, 4J42, 4J33, 4J34
Executive Standard: YB/T 5234-93
Uses: Used for making and ceramic sealing. Suitable for matching sealing of electric vacuum devices and 95% Al2O3 ceramics. In the temperature range of -60 °C ~ +600 °C with 95% Al2O3 ceramic similar linear expansion coefficient.
Delivery status: strip, wire, round bar, forgings.
3. Low expansion soft magnetic alloy FeNi36, FeNi32CO4Cu, Invar

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